The prevalence of obesity has risen significantly in the past decade in the United States and many other developed countries, (Fiegal et al, Int. J. Obesity 22:39-47 (1998), Mokdad et al, JAMA 282:1519-1522 (1999)). Because obesity is associated with a significantly elevated risk for type 2 diabetes, coronary heart disease, hypertension, and numerous other major illnesses, and overall mortality from all causes (Must et al, JAMA 282:1523-1529 (1999), Calle et al, N. Engl. J. Med. 341:1097-1105 (1999)), weight reduction is critical for the obese patient (Blackburn, Am. J. Clin. Nujtr. 69:347-349 (1999), Galuska et al, JAMA 282:1576 (1999)). There is good evidence that pharmacotherapy can enhance weight loss when combined with interventions aimed at changing life style (National Heart, Lung and Blood Institute, Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: the evidence report, NIH Publication No. 98-4083, September 1998). Yet, the available pharmacological therapies to facilitate weight loss fail to provide adequate benefit to many obese patients because of side effects, contraindications or lack of positive response (National Heart, Lung and Blood Institute, Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: the evidence report, NIH Publication No. 98-4083, September 1998). Hence, there is impetus for developing new and alternative treatments for management of obesity.
Zonisamide (ZONEGRAN®) is a marketed antiepileptic drug (AED). In short-term clinical trials of zonisamide in epileptic patients taking other concomitant AEDs, a small degree of weight loss was observed as an adverse effect in a small percent of patients (Oommen and Matthews, Clin. Neuropharmacol. 22:192-200 (1999)). The anticonvulsant activity of zonisamide is believed to be related to its sodium and calcium channel (T-type) channel blocking activity (Oommen and Matthews, Clin. Neuropharmacol. 22:192-200 (1999)). This drug is also known to exert dopaminergic (Okada et al, Epilepsy Res. 22:193-205 (1995)) as well as dose-dependent biphasic serotonergic activity (Okada et al, Epilepsy Res. 34:187-197 (1999)).
Topiramate (TOPAMAX®) is an AED that has been demonstrated in clinical trials of human epilepsy to be effective as adjunctive therapy in treating simple and complex partial seizures and secondarily generalized seizures (Faught et al, Epilepsia 36(S4):33 (1995); Sachdeo et al, Epilepsia 36(S4):33 (1995)). It is currently marketed as adjunctive therapy for partial onset seizures or primary generalized tonic-clonic seizures.
Bupropion, marketed as an antidepressant, has a pharmacological action dissimilar to that of zonisamide or topiramate. Bupropion has been shown to cause significant weight loss in patients presenting with primary obesity (Gadde et al, Obes. Res. 9(9):544 (2001)).
The present invention results, at least in part, from studies demonstrating that zonisamide is more effective than placebo for weight loss in obese subjects. The use of zonisamide (or other weight-loss promoting anticonvulsant) and bupropion (or other compound that enhances monoamine (e.g., serotonin, norepinephrine and/or dopamine) turnover in the brain via uptake inhibition or other mechanism) provides an effective treatment for obesity with few side effects.